Cranks but wont start 86 carrera

[JQ911]

hi, i drove 2 miles from the house to the grocery and everything went fine. coming back from the grocery after 5 mins i crank it it goes but does not start. The only thing unusual i did was not driving hard since the engine is not yet on its normal temp. now im stuck at the parking lot. how can i get this thung running? what to check? patience as im new with air cooled engines. i drove 90 miles a few days ago without any problems. i have extra dme with me

[Joe Bob]

If you have quick start, shoot some in the intake.....if it coughs or starts, it's fuel. No cough or start it's likely your DME relay. It clicks when you turn the key....it's under the seat.

It's a recommended plug in piece for anyone running a DME style fuel injection system.

[ivangene]

if you have a spare DME relay - swap it - if not remove the one under the seat and whack it a couple times

also the fule pump might have died (ask me how I know) - BUT - if you can reaach it under the front an knock it it might re-start temporarilly (mine did)

[kidrock]

like Joe Bob says....plug in your DME relay replacement first. This is the most common issue with Carreras.

No start? You can run a couple of simple tests in the parking lot, but I personally prefer to have AAA tow it home for me.

Fuel and spark, fuel and spark. Test for fuel like Joe Bob described. If it starts then quickly dies, then it's most likely a bad fuel filter or fuel pump. If it doesn't start after introducing fuel into the intake, then you need to check for spark. I prefer to pull a plug wire, install a spare plug into the end, and use a jumper wire from the base of the plug to a good ground (away from all fuel sources). Have a friend turn the ignition while you observe spark.

Let us know the results.

[JQ911]

so far i whacked the dme and checked the distributor. dme swapped but nothing. looks like fuel pump as it is starved. called AAA so i can use mu premium membership. will keep you posted and will bring to euro motors our local porsche technician who happens to have a carrera as well,

[JQ911]

so the tow came and when it was being winched up the flatbed i see something leaking under. hmmm does look good

[OK Porsche 911]

Fuel line at the pump or the one that (behind the engine fan) feeds the injector rails??

[JQ911]

driver says you dont have to worry that oil is not yours. it came from the previous car

[KTL]

cyl head temperature sensor or reference sensors that shoot the flywheel also can cause intermittant no start

[Joe Bob]

^^^^
Yep, but less down the possible percentage of failure mode and the less easy to fix on the road....%^)

BTW, if IT IS one of the sensors, there are threads on the BMW version which is 1/2 the price. Isn't there two flywheel sensors for the 3.2?

Never could get an answer on if the BMW ones work for the 3.6.

[KTL]

Agreed. But the reference sensors can be "fixed" by jiggling the wires. One of the sensors only needs to "see" the set screw in the flywheel during cranking. Once the engine's running, engine don't care if that sensor be workin' any more!

[Joe Bob]

Haven't had the pleasure of a sensor failure....good to know.

[JQ911]

So the car is now at Euro Motors and I will report once I get the results. While it's there, I asked them to check others as well:

1. Howling sound on the engine and fan causes to vibrate. It only happens once the engine is hot or driven more than 30 miles. Could be the alternator bearing.
2. Lower it down to euro height as mine looks like its on stilettos ready for the Paris-Dakay Rally.
3. Oil change

It was damn pretty cold while I was pulling out the DME relay kneeling on the pavement, going in and out / front and back of the car trying to figure out how to start it. Good thing I was parked in-front of the New York Sports Club and the view with those ladies doing the treadmill kept me warm...

My souvenir shot...

[ivangene]

man, she's a beauty !

I highly recommend corner balance when lowering - esp the front, weighted with a driver

[JQ911]

Originally Posted by ivangene

man, she's a beauty !

I highly recommend corner balance when lowering - esp the front, weighted with a driver

Hi Ed, yes, alignment and corner balanced was what Euro Motors suggested.

[JQ911]

Oh well, the DME relay was toasted and my spare either was bad or I did the swap incorrectly. When the shop replaced the DME problem solved. However, they found a small leak most probably coming from one of the sensors at the back and might do a partial drop. While they are at it, I also dropped off my sound deadening pad and have them installed.

OT - Had it lowered and aligned while it was there last week and it looks nice but have not tested it yet. Corner balancing maybe on the list next right after fixing the oil leak.

[McLaren-TAG]

Troubleshooting 101 so I'm sure your shop knows but when they plug in the old DME relay the car won't start again? There's not much you can screw up plugging in a replacement DME so I'd take the opportunity to confirm your 'spare' is either broken or good. No sense carrying around a questionable DME relay with you.

Some of the no start issues that are related to the speed sensors or CHT sensors are temperature related and may only exhibit the symptom when they reach a certain temperature.

[JQ911]

Originally Posted by McLaren-TAG

Troubleshooting 101 so I'm sure your shop knows but when they plug in the old DME relay the car won't start again? There's not much you can screw up plugging in a replacement DME so I'd take the opportunity to confirm your 'spare' is either broken or good. No sense carrying around a questionable DME relay with you.

Some of the no start issues that are related to the speed sensors or CHT sensors are temperature related and may only exhibit the symptom when they reach a certain temperature.

Shop tried a new DME and car started. They took out the new DME and tried the one previously installed just to check and it won't start. Can't find the spare DME I swapped it with previously and must have left it inside the tow truck. I bought a good and tested spare DME now.

When I took out the bolt of the DME relay, I tried pulling the relay toward the front of the sports seats but would not budge in. I can hardly put my hands under the sport seat (driver's) to do the swap even if the sports seats where all the way to the back. I tried to move it forward and gain access from behind, I was able to get hold and feel the relay in my right hand but could not see to unplug it. My rear seat by the way is elevated due to a non-working sub-woofer installed by PO which left no room for my elbows to work its way around. Either I was too lazy to exert extra effort or I was just to conscious as people at the NY Sports Gym started to look at me, so I acted as if everything was under control

The only access I had then is by taking out the bolts of the sports seats. You can just imagine me kneeling/sitting at a grocery parking lot in-front of a gym at 30F with the freaking wind blowing. Is there an easy way replacing the relay without taking out the driver's seat? This will be one of my projects during the summer. DIY trouble shooting 101.

When the tow truck came everything was in disarray and I could not even find my spare DME and long nose I used in trying to pull out the relay (must have left it in the tow truck).

[KTL]

The relay harness is fastened on one of the studs that also captures a clamp for the big fat wiring harness. So you certainly could take the relay off that stud and fasten it someplace else that is easier to reach, as long as there's a decent amount of extra wire in the relay pigtail/harness. I recall on my own car there is a bit of extra wire in there so the move should be no problem. Just make sure to fasten it down and not let it flop around. Too much bouncing around can make the relay fail.

No worries about the difficulty in removing the seat. I've yanked the seats on these cars dozens of times and even with my own "custom" socket head screws, using a ball-end hex key, I still sometimes find myself getting aggravated.

Technically the corner balance should be done first before the alignment. If you have to fiddle with the ride height after it being lowered & aligned, you will mess up the alignment. Especially so on the front. The rear is not as sensitive to height change in terms of toe. However the front end is quite sensitive. So after the corner balance, check the toe. Camber & caster not that big of a deal for a street car. Toe however is important!

Glad to hear it was a simple fix. Sorry to hear it wasn't a fix you could do, considering you had the exact part needed to git 'er done!

Now's the time to take a look at those reference sensors so you can plan for the future. Like McLaren-Tag said, they don't give you any warning and are notorious for intermittant behavior when going bad. The failure of these is typically the rubber jacket around the wire gets brittle due to heat. Then it splits open and allows moisture in, which as we know doesn't play nice with the invisible magic we call electricity.....

[JQ911]

Moving forward, Spring project:

1. DME Relay - Transfer to a more accessible place for easy reference/swap/install.
2. Sensors - Time to do preventive maintenance and possibly change both. I tried to do some reading during my free time and found an alternative part which cost half the price. Has anyone used it and never had an issue except for the length, referring to the BMW sensors.